Purpose
Cover crops can provide multiple agroecosystem services to crops produced in conservation agriculture systems. South African grain producers in the Mediterranean climate region are reluctant ...to integrate cover crops in rainfed systems since cover crops replace cash crops leading to financial losses. Using cover crops as fodder can help cover input costs, while providing a range of advantageous services to the cropping system. The aim of this study was to investigate how cover crop mixtures and the utilisation of cover crops affect soil quality, the quality and quantity of the mulch as well as wheat (
Triticum aestivum
L.) produced in the subsequent year.
Methods
A two-year study was conducted in the Western Cape Province of South Africa. In Year 1, diverse legume and cereal-based cover crop mixtures were partially grazed, cut and material removed for haymaking, or left unutilised as a mulch. In Year 2, spring wheat (
Triticum aestivum
L.) was planted to investigate the effects of cover crop mixtures and utilisation method on subsequent spring wheat yield.
Results
Cover crops used as hay or for grazing did not affect (
P < 0.05
) grain yield of wheat that followed in rotation. Legume-based cover crop mixtures increased (
P < 0.05
) wheat grain protein content regardless of utilisation method. Soil quality and nitrogen content improved (
P < 0.05
) when cover crops were grazed.
Conclusions
Cover cropping can be used by South African grain producers as an important agronomic tactic to improve system productivity and support sustainable intensification of rainfed cropping systems.
The paper intends to present the life and the works of the distinguished Iranian scholar Paul Horn (1863-1908). A native of Saxony in Eastern Germany, he spent most of his life in Strasbourg where he ...also died, at an early age, and completely exhausted, in 1908. The biography of this scholar is, in many respects, exemplary. Within two decades, Paul Horn was able to accumulate an enormous amount of competence enabling him to publish remarkable works not only in the field of Iranian studies but also in that of a more recent academic discipline, turcology (where Horn has to be considered as a pioneer). We find in his life both the hardships of a Privatdozent (unsalaried lecturer) at the prestigious Kaiser-Wilhelms-Universität, the necessity to ask permanently for grants and subsidies, and ambitious publication projects such as the Persian divan of Sultan Selim I. Paul Horn represents a perhaps typical case of German oriental scholarship at that time. This scholarship is characterized by versatility, the capacity to penetrate into the most diverse fields of research—sometimes with an amazing rapidity—and to produce works of fundamental importance. Archival documents further provide us with a great number of elements which can illustrate the very special relationship of these scholars with the countries presenting the focus of their research, i.e. the “Orient”.
We investigated the effect of heat and moisture stress on total factor productivity in crop farming under experimental farm conditions. Heat stress is the number of days during the growing season ...during which the maximum temperature exceeds 24.9 °C. Total rainfall is treated as a basic factor of production and periodic moisture stress, or lack thereof, is the number of rainfall days during the growing season. All models controlled for the cumulative soil benefits arising from minimum tillage, which is the main objective of the experiment. Model specification was evaluated using likelihood ratio tests and three are wor thy of note. The study site received 329 mm of rainfall on average on 22 rainy days per season during the period 2002-2015, while the maximum temperature typically rose above 24.9 °C on 33 days per growing season. The average efficiency of the plots in the long-term crop rotation experiment increased at 3.4% per year from a base of 60% to the most recent level of 78%. Neither heat nor moisture stress changed significantly over the study period. Heat stress was found to reduce efficiency by 1.75% per hot day and rainfall increased efficiency by 1.45% for each additional rainy day. However, the interaction of heat and moisture stress lowered productivity overall.Significance: • This study contributes a new approach to modelling the effect of climate on agricultural productivity using a new metric of heat and moisture stress. • We quantify the marginal effects of rising temperatures and rainfall events and evaluate several potential specifications of heat and moisture stress variables.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The Southern African Development Community (SADC) region is facing significant energy challenges related to the access to modern energy services, and problems associated with the human health and ...environmental challenges of current traditional energy systems. Many existing power plants, across the region, have reached the end of their economic life and are in urgent need of replacement. SADC recognizes the existing energy challenges and will need to, among others, rapidly develop and implement renewable energy, as a matter of priority. Despite the SADC region enjoying enough solar irradiance, solar power generation has not received the much needed attention. Besides that, the SADC countries need to develop policies that will favour more participation of the independent power producers (IPPs) so that they can contribute to harness the solar energy available. For this to happen, the full range of solar energy activities in the SADC region needs to be understood by all policy makers and regulators, local and global investors, developers and project promoters in the region. Main objective of this review is to; put forward country wise information on present status and efforts done so far to implement solar technologies in SADC region. Also, discussed in detailed, various solar energy projects which are under planning and policies which will see a bigger role of solar energy in region's future energy mix.
There is limited soil research on semi-arid, grazed no-till crop and pasture systems. The long-term (10 years) effect of three grazed no-till dryland crop and pasture rotation systems, and perennial ...lucerne pasture were assessed on soil carbon (C) and nitrogen (N) stocks, soil organic matter functional pools and selected soil quality parameters in the Overberg, South Africa. The largest soil C and N stocks (0-30 cm) were found in crop-pasture systems containing wheat and medic/clover (70.2-74.9 Mg C ha
−1
and 8.3-8.4 Mg N ha
−1
), compared with perennial lucerne pasture (63.4 Mg C ha
−1
and 7.7 Mg N ha
−1
) or cropping-only systems (54.7-58.9 Mg C ha
−1
and 6.3-6.7 Mg N ha
−1
). Significantly higher labile C and N (free particulate organic matter fraction) contents were observed in crop-pasture systems (1.37-1.74 g C kg
−1
and 0.107-0.110 g N kg
−1
) than in continuous cropping systems (0.9-1.0 g C kg
−1
and 0.042-0.045 g N kg
−1
), attributed to higher annual C and N inputs and lower extent of soil disturbance. Significant positive correlations were found between soil C and N functional pools and soil quality parameters (soil respiration, effective cation exchange capacity and aggregate stability) and wheat yields. The results show the importance of the medic/clover pasture and wheat rotations in enhancing soil quality in the Overberg region.
Wheat (Triticum aestivum) is planted widely in the Western Cape of South Africa in conservation agriculture systems. Although most producers rely on tine openers to establish wheat, the interest in ...planters with disc openers is increasing. Given that the soils in the Western Cape are highly variable, it is hypothesised that soil quality may influence the choice of openers to use. The aim of this study was therefore to evaluate the effects of tine and disc openers in soils of contrasting qualities, to discern whether soil quality is a factor to consider when choosing between tine and disc openers. The study was conducted on Langgewens Research Farm. Soil disturbance was evaluated directly after sowing wheat with tine and disc openers. Tine openers disturbed the soil more (p < 0.05) than the disc openers in low quality soil, and did not differ (p > 0.05) from the disc opener effect in high quality soil. Establishment of wheat with disc openers resulted in an 11% yield increase as opposed to when established with tines. Grain yield was 24% higher in the high quality soils compared with the low quality soils. To ensure high yields, the importance of ensuring that soil quality is maintained, is stressed.
This article examines the functions and the significance of picture postcards during World War I, with particular reference to the war in the Ottoman Lands and the Balkans, or involving the Turkish ...Army in Galicia. After the principal types of Kriegspostkarten – sentimental, humorous, propaganda, and artistic postcards (Künstlerpostkarten) – have been presented, the different theatres of war (Balkans, Galicia, Middle East) and their characteristic features as they are reflected on postcards are dealt with. The piece also includes aspects such as the influence of Orientalism, the problem of fake views, and the significance and the impact of photographic postcards, portraits, and photo cards. The role of postcards in book illustrations is demonstrated using a typical example (F. C. Endres, Die Türkei (1916)). The specific features of a collection of postcards left by a German soldier who served in Turkey, Syria, and Iraq during World War I will be presented at the end of this article.
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